While Uganda's politicians and social media are abuzz over a sensational letter reportedly written by a top security official about a high-level assassination plot, police have dutifully harassed the mainstream press in a bid to suppress the chatter.

Police spent the entire day Tuesday interrogating three journalists from the private Daily Monitor over their coverage of a letter by the Coordinator of Security Agencies, Gen. David Sejusa (better known as Tinyefuza), Editor Charles Mwanguhya told me.

The general, known for his occasional defiance of the presidential State House, claimed in the letter there was a plot to assassinate senior government officials to ensure President Yoweri Museveni's son, Brigadier Muhoozi Kainerugaba, assumes the presidency in 2016, the Monitor reported. Those opposed to the son's ascension to office--dubbed the "Muhoozi Project," Sejusa claims--face imminent threats by security personnel, according to the Monitor's coverage last week. The Monitor quoted Sejusa confirming that he authored the letter.

Although the newspaper published authorities' denunciation of Sejusa's accusations, the Criminal Investigations and Intelligence Directorate summoned Managing Editor Don Wanyama and senior reporters Richard Wanambwa and Risdel Kasasira over the story. "They were interested to know how we got the letter Gen. Sejusa wrote, but there is no way we could reveal our sources since it goes against our code of ethics," Wanyama told me. The police did not officially charge the journalists, but accused them of withholding information and ordered them to return at 11 a.m. today. "It is some kind of intimidation exercise," Wanyama said.

Journalists who tried on Saturday to cover Gen. Sejusa's return to Uganda from an official trip abroad were blocked or detained, Monitor journalist Isaac Kasamani told me. Kasamani and seven other print and broadcast reporters were prevented from passing the security checkpoint at Entebbe airport, the Ugandan Human Rights Network for Journalists reported. Security officers threatened and detained private NBS Television reporter Ivan Kabaale for four hours at the Entebbe police station, the human rights network said. In the end, the general did not show up.

But the worst violation of press rights occurred last week, when security agents detained popular radio host James Kasirivu on May 8, after he reported on Sejusa's claims, and released him two days later. Plainclothes agents picked up the host from Endigito Radio in the southwestern town of Mbarara and held him at Kireka Special Investigations Unit in Kampala, Kasirivu told me. Kasirivu suspects the detention is linked to his comments over Sejusa's letter, since the agents requested recordings of the program. "I didn't go into detail over the case, just reported the issue, but immediately after airing [the report] they came to request the recording," he said.

The boss of the Special Investigations Unit, Beata Chelimo, said Kasirivu was accused of receiving 870 million Ugandan shillings (US$337,000) in illicit payments from a fraudulent traditional healer, according to news reports. But the agents did not tell Kasirivu about these allegations during his detention and the alleged funds were not found in his bank account, he said.

The presenter of the current affairs program "World Express" is no stranger to government intimidation. In January, the state-controlled broadcast regulator, the Uganda Communications Commission, ordered Radio Endigito's management to suspend Kasirivu or risk losing its operating license, local journalists and news reports said. "Without explanation, they ordered my suspension," Kasirivu told me. "They just communicated through the boss." Kasirivu believes the temporary suspension was in retaliation for hosting four member of Parliament critical of the government. The same station also temporarily suspended Kasirivu in December 2010, after he reported on an opinion poll that gave the former opposition contender Kizza Besigye a clear lead in upcoming elections.

State House intimidation against radio stations in western Uganda increases during election periods since the region is routinely a political stronghold for the ruling party, Kasirivu said. "Few presenters make political comments in western Uganda these days," he said, because they fear retribution from their bosses who heed the directives of the ruling party. In January, police temporarily detained three staff members of the Twerwaneho Listener's Club, a local civil society organization that produces radio programs covering human rights and governance issues in western Uganda, accusing them of making defamatory statements against Uganda's first family, news reports said. In March, police froze the club's bank accounts, despite Ugandan law that stipulates only courts are empowered to do so, according to reports.

Police and security forces, under the auspices of the state, appear determined to intimidate any media house in the country that provides coverage to those critical of the ruling party or of the growing rebellion within the party itself. Museveni's 2013 New Year's message accused the media and politicians of "indiscipline" and warned "firm steps will be taken," according to news reports.

These "firm steps" will undoubtedly increase as Uganda creeps towards 2016 elections and the ruling party's grip on power appears increasingly tenuous. But authorities' knee-jerk, sometimes violent reaction to negative press coverage misses the point that Ugandan citizens and the press alike are already discussing via social media sensitive issues such as the alleged "Muhoozi Project"--despite efforts to suspend radio hosts and interrogate print reporters. As one tweet reads, "When Gen. David Sejusa sneezes the whole of Uganda catches a cold."

[Reporting from Nairobi]Tom Rhodes is CPJ's East Africa consultant, based in Nairobi. Rhodes is a founder of southern Sudan’s first independent newspaper. Follow him on Twitter: @africamedia_CPJ